By H C van de Graaf and A P Smits, Delft Soil Mechanics Laboratory
This paper was first publsihed in GE’s January 1983 issue.
A diving bell for carrying out seabottom site investigations has been in almost continuous use since 1976 when MISSION I (Manned Installation for Subsea Soil Investigations) was developed and built as a joint venture of Vriens Diving Company and Delft Soil Mechanics Laboratory for use on the Eastern Scheldt storm surge barrier. MISSION I was used initially for the preconstruction site investigation and is now doing the control tests for the soil improvement work. It is fitted with a 60 tonne hydraulic jack and does cone penetration tests, 66mm continuous soil sampling, in-situ density measw’ements, etc.
The success of MISSION I led to the construction of a larger diving bell, suitable for offshore site investigations and including the capability for doing rotary and percussive boring. Although equipped and used for cone penetration testing, etc., the award of a contract in April 1981 for a project in Newfoundland provided the opportunity to install rotary drilling equipment